This invention relates to a fluid spraying monitor and, in particular, to one adapted for use in cleaning internal surfaces of large-scale combustion devices.
During the operation of large-scale combustion devices, such as boilers burning fossil fuels, slag and ash encrustations develop on internal surfaces of the device. The presence of these deposits degrades the thermal efficiency of the combustion device. Therefore, it is periodically necessary to remove such encrustations. Various techniques are presently used. In some cases, vibration is used to mechanically remove such deposits. Devices referred to as xe2x80x9csootblowersxe2x80x9d are used to project a stream of a fluid cleaning medium, such as air, steam or water, against the internal surfaces. In the case of long retracting type sootblowers, a lance tube is periodically advanced into and withdrawn from the boiler and articulated to rotate or oscillate to direct one or more jets of cleaning medium at desired surfaces within the boiler. Sootblower devices are also used which are stationary and maintained in a position within the boiler. Sootblower lance tubes project through openings in the boiler wall, referred to as wall boxes. In cases where it is desired to clean the interior wall area surrounding the wall box, so called wall blowers are used. These devices incorporate a lance tube with nozzles directed back at the wall through which the lance tube is projected.
Another class of boiler cleaning devices is used which are designed to clean a wall surface other than the one in which the wall box is installed using water as the cleaning fluid. These devices are sometimes referred to as xe2x80x9cwater cannonsxe2x80x9d. They involve the use of a monitor or nozzle positioned within a wall box that creates a jet of water or another fluid which passes through a portion of the interior of the boiler and strikes an opposing wall or other surface to be cleaned. Early versions of these devices were manually articulated to allow the stream to be aimed at particular areas to be cleaned. More recently, however, articulating devices operated under programmed numerical control periodically cause the water cannon lance to trace a prescribed spray pattern on the opposing wall or other surface to be cleaned. This invention is related to such a water cannon device which will also be referred to in this description as an articulating water monitor cleaning device.
In accordance with this invention, an articulating monitor-cleaning device is designed principally for ejecting water which incorporates a pair of orthogonally oriented articulating four-bar linkages which are mechanically actuated. One of the linkage arms or links is coupled to the lance tube near its inlet end. The other discharge end of the lance tube where a nozzle is present is mounted to the wall box and is allowed to freely pivot at the wall box. Using a pair of rotary actuators, each of the pairs of four-bar linkages can be actuated to a prescribed angle. By adjusting the angles of the four-bar linkages, a prescribed aiming position on the lance tube can be achieved. Under programmed control, a desired motion sequence can be executed to trace a desired pattern for the jet ejected from the water lance.
The device according to this invention further includes mechanisms to improve the mechanical stability of the drive. This is principally achieved by providing redundant four-bar linkages which are not driven but follow the motion of the actuated or driving four-bar linkage. The geometric relationship of the elements comprising the four-bar linkage are selected such that movement of an actuating axle translates directly to an equivalent motion of the lance tube over a range of motion. This is achieved by four-bar linkages which are based on links defining a parallelogram, that is, opposing links have equal lengths. Another feature of this invention provides a system including a subassembly which can be conventionally mounted to the associated boiler.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings.